1. Technical Field
The present invention relates to a tool path display apparatus that displays a tool vector of a machine tool.
2. Description of Related Arts
Some numerical control apparatuses for controlling a machine tool are used together with a tool path display apparatus that displays a tool path along which a tool moves. An operator uses visual information on a tool path displayed by the tool path display apparatus, in order to evaluate a machining process. For evaluation of a machining process, it is advantageous to evaluate a tool vector representative of a posture of a tool, in addition to a path representative of a moving path of a tool tip point corresponding to a portion for machining. FIGS. 11A and 11B are schematic views illustrating an effect of a tool posture on a shape formed by machining. FIG. 11A shows a machined shape obtained when a tool 100 has a posture substantially perpendicular to a machined surface P. On the other hand, FIG. 11B shows a machined shape obtained when the tool 100 has a posture inclined to the machined surface P. As can be clearly seen in comparison of FIG. 11A and FIG. 11B, even though a tool tip point 102 is positioned at the same point, a shape of the machined surface P can be completely different, depending on the tool posture.
Japanese Patent No. 4689745 discloses a tool vector display apparatus that displays an actual path obtained from actual position information of a tool tip point detected by a detection device and also a posture of a tool as a tool vector on the actual path. This related art is designed to display a tool vector together with an actual path so as to allow a tool posture to be visually inspected in a portion where an error possibly occurs in a machined shape.
However, it has been found difficult to identify the cause of the error in a machined shape only with information displayed by the tool vector display apparatus taught by Japanese Patent No. 4689745. Therefore, there is a need for a tool path display apparatus that provides visual information effective to identify the cause of an error in a machined shape.